1. Field of the Invention
The present invention relates to a storage, and more particularly to a bidirectional storage capable of continuously functioning of FILO (First In Last Out).
2. Description of the Background Art
A storage functioning of FILO (hereinafter such storage is also referred to as a "FILO") sequentially inputs data to be output in order reverse to input order.
Since the FILO according to the prior art operates by pushing and popping, in the case where only one FILO is used, a second set of data cannot be processed of FILO immediately after a first set of data are processed of FILO. The reason is that the first set of data are destroyed if another set of data are input to the FILO before the first set of data are completely read.
FIG. 53 is a block diagram showing a structure in which two conventional FILOs are used to continuously obtain processings of FILO for first and second sets of data. Input data DIN is distributed for its each set and given to a FILO 1 and a FILO 2 by a demultiplexer DMUX0. Either of outputs from FILO 1 and FILO 2 is sent as output data DOUT by a multiplexer MUX0.
For example, when the input data DIN gives the first set of data to the demultiplexer DMUX0, the first set of data are sequentially input to the FILO1. When the input data DIN gives the second set of data to the demultiplexer DMUX0, the second set of data are sequentially input to the FILO2 and the data given to the FILO1 are output as the output data DOUT through the multiplexer MUX0 in reverse order. Then, when the data given to the FILO2 are output as the output data DOUT through the multiplexer MUX0 in reverse order, the input data DIN gives a third set of data to the demultiplexer DMUX0.
In the prior art, a pair of FILOs which are alternately selected should be used to continuously perform the processings of FILO for plural sets of data. Accordingly, a region for storing data should be twice as much as a set of data.